The main semiconductor device component of the integrated circuit, especially of the ultra-large-scale integrated circuit, includes a metal-oxide-semiconductor field effect transistor (MOS transistor). With the continuous development of the integrated circuit manufacturing technology, the technology node and geometric dimension of semiconductor devices continue to decrease following the Moore's Law. When the size of a semiconductor device is reduced to a certain extent, various secondary effects due to the physical limit of a semiconductor device may successively occur, and as a result, scaling down the feature size of a semiconductor device becomes more and more difficult. In the field of semiconductor manufacturing, one of the challenges is to solve the large leakage current problem of semiconductor devices. The large leakage current of a semiconductor device is mainly caused by the continuous decrease of the thickness of the conventional gate dielectric layer.
The conventional solutions to the large leakage current problem include use of a high-K gate dielectric material to replace the traditional silicon oxide gate dielectric material and to use a metal as the gate electrode to avoid the Fermi level pinning effect and the boron permeation effect occurring between the high-K material and the traditional gate electrode material. Introducing a high-K metal gate reduces the leakage current of semiconductor devices.
Although the introduction of a high-K metal gate can improve the electrical performance of semiconductor devices to a certain extent, the electrical performance of semiconductor devices formed by conventional methods still needs to be improved. The disclosed device structures and methods are directed to solve one or more problems set forth above and other problems.